Combined radiant and convection superheater



P 1940.. w. H. ARMACOST I 2,213,185

COMBINED RADIANT AND CONVECTION SUPERHEATER Filed June 18, 1938 2 Sheets-Sheet 1 INVENTOR VIM 141" fl flrmaws' BY 0/ w ATTO R N EY Sept. 3, 1940.

W. H. ARMACOST Filed June 18, 1938 2 Sheets-Sheet 2 P r- '7 PH P95 P Z5 J 14 {g i-t-ija fifl ./7--- W1" e H T ll y 1 I I I I i 12- gr/- a a ;5"" k a INVENTOR ATTORNEY 20 Figs. 2 and 3 are sectional views on the lines elements I2 on the wall 2. Since the remaining 20 Patented Sept. 3, 1940 g UNITED STATES PATENT OFFICE COMBINED RADIANT AND CONVECTION SUPERHEATER Wilbur H. Armacost, Scarsdale, N. Y., assignor to The Superheater Company, New York, N. Y.

Application June 18, 1938, Serial No. 214,446

8 Claims. (Cl. 122481) This invention relates to boilers. for high steam also act as a slag screen therefor. The outlet temperatures .and pressures and particularly to header for the convection superheater is desigan improved arrangement of the various heat nated by the numeral 28. A reheater 29, an absorbing surfaces thereof. In such boilers much economizer 3B and an air preheater 3I are also of the heat absorbing surface is located within shown in the olftak'e 24 from the furnace. the furnace and it is an object of the present in- As shown in Fig. 1, the side walls 3 and 4 are vention to provide a novel correlation of the wa-- lined with steam generating tubes 32 connected ter and steam heating surfaces in the furnace at their upper ends to the steam space of drum with respect to each other and the fuel burners I l and receiving water from lower headers 33 and also with respect to convection heated surconnected to the water space of the drum I4 by faces located in the offtake from the furnace. downcomers 34 as shown in Fig. 2.

The invention will be best understood upon con- As mentioned above the wall 2 is located at sideration of the following detailed description such a distance from the wall that the flames of an illustrative embodiment thereof when read from the burners I0 therein do not impinge subin conjunction with the accompanying drawings, stantially on the heat absorbing elements on the in which: wall 2. The flames and gases from the burners Fig. 1 is an elevational view, partly in vertical I!) are cooled substantially by the water cooled section, of a boiler embodying the present insurfaces 32 on the side walls 3 and 4 before reachvention; and ing a position in front of the radiant superheater 2-2 and 3-3, respectively, in Fig. l. radiant superheater elements 23 are located on The furnace of the boiler shown in the drawthe wall I above the burners ID the flames are ings contains all of the steam generating elements projected away from these elements, and the of the boiler and part of the steam heating or gases are cooled by the heat absorbing elements superheating elements, all of the furnace walls in the lower portion of the furnace before they 25 being substantially completely faced or lined with rise to a position to impart heat to the elements heat absorbing elements except the wall I through 23. Therefore, in operation all of theradiant which project the fuel burners l0 fed by the steam heating surface is substantially free from mill II. The opposite wall 2 (Fig. 3) is located flame impingement and is located in zones of at such a distance from the wall I that the flames relatively low temperature so it will not suffer 0 from the burners I0 do not impinge on the heat overheating. The flames issuing from the burnabsorbing elements on this wall. The heat abers II] are flanked on either side by water cooled sorbing surfaces on the wall 2 comprise radiant surfaces 32 to which they rapidly give up much of superheater elements I2 covering the areas from their heat by radiation and since they do not .35 each side edge of wall 2 part way toward the cenretain their directional velocity because of the ter thereof, the middle portion of the wall being furnace depth, they do not impinge on that steam lined with steam generating tubes I3. These heating surface I2 on the wall 2 opposite to the tubes receive water from the steam and water burners. Upon turning upwardly, the flames are drum I4 through the lower header I5 connected further cooled by the remaining water cooled to the drum by downcomers I6 (Fig. 1). surfaces and by the steam heating surface 23 40 The inlet headers H for the radiant superheatuntil they have reached the opening of the furer tubes I2 are connected to the steam space of nace offtake, whereupon they have been cooled drum I4 by pipes I8 and the outlet header 20 to such an extent that the cross flow of the gases therefor is connected by pipes H to an inlet headover the upper portions of the steam heating er 22 supplying radiant superheater tubes 23 tubes on the wall I and into the offtake as shown 45 covering the entire width of wall I (Fig. 2) above in Fig. 2, does not overheat said tubes. the burners Ill. The upper portions of the super- The furnace leaving temperature may be varied heater tubes 23 extend across the offtake 24 and by manipulating the burners to vary heat abare connected at their upper ends to the inlet sorption in the furnace. In the embodiment header 25 of a convection superheater located shown the burners are so grouped that under 50 in the offtake. Where they cross the offtake 24 reduced loads the flames may issue from the top the upper ends of the radiant superheater tubes burners, thereby a g cooling y the parts are .arranged to permit gases from the furnace of the heat absorbing elements in the lower porto pass therebetween to impart heat to the eletion which results in a higher offtake temperaments 26, 21 of the convection superheater and ture and consequent higher superheat. Alter- 5.5

natively, the flames may issue from the bottom burners with resultant lower oiftake and superheat temperature. The flames may issue from the side or center burners which would influence the offtake or superheat temperatures by the greater or lower absorption, respectively, of the side water walls 32, or the flames may be projected to a greater or lesser distance across the furnace toward the Water or steam heating surfaces of the wall in Fig. 3 and effect the superheat by such means of control.

Thus, according to the invention there is a cooperative relation between the location of the steam heating and the steam generating surfaces and the location of the burners with respect thereto which is particularly applicable to high pressure, high temperature steam conditions in that the steam heating tubes I2, 23 must be well guarded against over-exposure to heat impingement due to both their temperature and thickness. As a consequence of such guarding against flame impingement, a less costly alloy may be used. In a high pressure generator of the type all steam generating tubes are within the furnace which also contains an amount of steam heating surface to satisfy the relatively high steam temperature required. The arrangement of the radiant superheating elements l2 on the side portions of wall 2 with steam generating tubes l3 therebetween also permits a desired increase or decrease of the superheating effect by replacing generating tubes 13 with superheating elements l2, or vice versa, while still maintaining the protection afforded by the water cooled side walls 32 against overheating these radiant superheating elements.

What I claim is:

1. In a boiler having a furnace provided with burners introducing fuel through one wall thereof; steam generating surfaces lining the adjacent walls of the furnace; steam heating surfaces lining the Wall opposite that in which said burners are located over areas extending part way from each outer edge of said opposite wall toward the center thereof, the width of said furnace being such that flames from said burners do not impinge on said opposite wall; and steam generating surfaces lining that portion of said opposite wall between the portions thereof that are lined by steam heating surfaces.

2. In a boiler having a furnace provided with burners introducing fuel through one wall thereof; steam generating surfaces lining the adjacent walls of the furnace; steam heating surfaces lining the wall opposite that in which said burners are located over areas extending part way from each outer edge of said opposite wall toward the center thereof, the width of said furnace being such that flames from said burners do not impinge on said opposite wall; an offtake for said furnace extending outwardly from the upper edge of the wall in which said burners are located; and steam heating surfaces lining the portion of the wall above said burners.

3. In a bolier having a furnace provided with burners introducing fuel through one wall thereof; steam generating surfaces lining the adjacent walls of the furnace; steam heating surfaces lining the wall opposite that in which said burners are located over areas extending part way from each outer edge of said opposite wall toward the center thereof, the width of said furnace being such that flames from said burners do not impinge on said opposite wall; an offtake for said furnace extending outwardly from the upper edge of the wall in which said burners are located: and steam heating surfaces lining the portion of the wall above said burners; said steam heating tubes having spaced portions extending across said offtake; and steam heating surfaces located in said offtake at a point beyond the steam heating surface extending across the offtake.

4. In a boiler having a furnace provided with burnerse introducing fuel through one wall thereof; steam generating surfaces lining the adjacent Walls of the furnace; steam heating surfaces lining the wall opposite that in which said burners are located over areas extending part way from each outer edge of said opposite wall toward the center thereof, the width of said furnace being such that flames from said burners do not impinge on said opposite wall; an offtake for said furnace extending outwardly from the upper edge of the wall in which said burners are located; steam heating surfaces lining the portion of the wall above said burners; said steam heating tubes having spaced portions extending across said ofitake; steam heating surfaces located in said oiftake; and steam heating surfaces lining a portion of the wall in which said burners are located over an area above said burners, parts of said surfaces extending in spaced relation across said offtake in advance of said steam heating surfaces therein.

5. In a boiler having a furnace provided with burners introducing fuel through one wall thereof; steam generating surfaces lining the central portion of the furnace wall opposite that in which said burners are located; and steam heating surfaces lining the remainder of said opposite wall over areas extending from each outer edge thereof to the portion covered by said steam generating surfaces, said furnace being of a width such that flames from said burners do not impinge upon the heating surfaces on said wall.

6. In a boiler having a furnace provided with burners introducing fuel through one wall thereof; steam generating surfaces lining the central portion of the furnace wall opposite that in which said burners are located; steam heating surfaces lining the remainder of said opposite wall over areas extending from each outer edge thereof to the portion covered by said steam generating surfaces, said furnace being of a width such that flames from said burners do not impinge upon the heating surfaces on said wall; and steam generating surfaces lining the side walls of said furnace for cooling the gases from said burners before said gases impart heat to said steam heating surfaces on the wall opposite said burners.

7. In a furnace for a steam generating unit substantially fully cooled by heat absorbing surface facing the walls thereof including all of the steam generating heat absorbing surface for the unit and other steam heating radiant heat absorbing surface; burner means; an offtake for the products of combustion; and convection heat absorbing, steam heating surface in said oiftake, some of said radiant steam heating surface extending across the opening of the oiftake as a slag screen through which the products of combustion pass and being the only heating surface between the furnace and the convection steam heating surface within the oiftake.

8. In a furnace for a steam generating unit substantially fully cooled by heat absorbing surface facing the walls thereof; fuel burners in a wall of said furnace; an offtake for the products of combustion extending from the wall in which said burners are located at a point above the latter; steam heating surface facing a wall area located above said burners and extending across the opening of the ofitake as a screen through which the products of combustion pass; steam heating surface facing the wall opposite said burners, that portion directly opposite said burners being spaced therefrom a distance to avoid undesirable flame impingement; and steam generating surface facing the remaining walls of the furnace. 

